What Exactly do I do to Stop Warwick's Ult.

--You don't Zhonya during Warwick ult, but if part of the issue is Warwick tanking all the turret shots, you can get behind your turret and Zhonya. At early levels the Warwick prolly can't tank the extra few seconds of tower shots.

--I think the advice is also to help you find a way to protect yourself while still building towards aggresive ap mid stats. As QSS only builds to , which won't provide you with ap stats. Unless you are an AD mid, in which case you can argue for it. Though Mercurial is generally more of a mid to late game defensive counter item.

--Warding is a much better option though, as you mentioned that QSS takes you away from early offensive stats and puts you behind in damage for both your lane and team fighting.

I have little experience as a jungler but my experience has all been with Warwick. I'll see if this helps even a little.

If your asking when in the beginning of the game you should place a ward, I'd hold them for actually a while. Warwick needs to farm to 6 before he's truly dangerous as a ganker, so he will usually be farming up to that point. I'd say keep track of your team's level and check the scoreboard (Tab) if he ever pokes his head out to see his level.

After Warwick hits 6 I'd say play safe like Millea suggested. Place wards and have your jungler help keep an eye out for him. If a ward spots him heading to you then head straight to tower and have your jungler help counter-gank. The thing about Warwick's ult is that he's just as stuck as you are, so if you can survive the burst and trap him under tower you can easily have him take a lot of free damage, sustain or no sustain. Warwick's damage early on isn't that great since he'll only have 1 offensive item (likely Wriggles) so he needs his laner to finish you off while he holds you. If he rushes defense, he loses a lot of jungle speed.

Once his ult is used Warwick has absolutely no CC and his only real tankyness early-mid game is through autos and his Q; if he isn't hitting anything he's soft. This is because his first 2 items will generally be Wriggles and Wits End, both offensive items. This makes him great 1v1 but weaker beyond that until he builds more tank items. It also makes him vulnerable to counter-ganks, since he has no real escape tool other than Flash/Ghost and his E (and that requires somebody to be low health).

In summary, try what you can to survive the burst, even if it's simply delaying the damage from the enemy mid somehow. Either way, make Warwick have to towerdive you and, assuming your jungle has CC, interrupt him and/or trap him there. Congrats, you likely have won the fight or at least went even. If you are 1v2 you are much more likely to lose, so either the jungler must help you or must gank another lane.

BTW if you rush a defensive item first, realize that you are sacrificing damage and kill potential for early survivability. That can make a huge negative difference in teamfights.